Question

If a force of 12 N acting on a body changes its velocity uniformly from 2 m/s to 5 m/s in 20 s then what is the mass of the body? A. 40 kg B. 48 kg C. 80 kg D. 96 kg​

Answer 1

Answer:

According to the question,

• Force (F) = 12 N
• Initial Velocity (u) = 2 m/s
• Final Velocity (v) = 5 m/s
• Time Taken (t) = 20 s

We need to find the mass of the object exhibiting the above information. We know that, Force = Mass × Acceleration. Therefore, Mass is nothing but:

⇒ Mass = Force / Acceleration   ...(i)

Since we are not given the Acceleration we need to find it using the given information. We know that,

⇒ Acceleration = Change in Velocity / Time Taken

⇒ a = (v - u) / t

Substituting the given information we get:

⇒ a = (5 - 2) / 20

⇒ a = 3 / 20 = 0.15 m/s²

Hence the acceleration of the body is 0.15 m/s².

Substituting the acceleration in (i) we get:

⇒ Mass = Force / Acceleration = 12 N / 0.15 m/s²

⇒ Mass = 80 kg

Hence the mass of the body is 80 kg.

Hence Option (C) is the correct answer.

Answer 2

Answer:

Question :-

✯ If a force of 12 N acting on a body changes its velocity uniformly from 2 m/s to 5 m/s in 20 s then what is the mass of the body?

Given :-

✯ If a force of 12 N acting on a body changes its velocity uniformly from 2 m/s to 5 m/s in 20 s.

Find Out :-

✯ Then what is the mass of the body?

Solution :-

We have :

• Force = 12 N
• Initial velocity u = 2 m/s
• Final velocity v = 5 m/s
• Time = 20 s

✭ In case of acceleration :-

As we know that :

☆ $\red{ \boxed{\sf{v =\: u + at}}}$ ☆

So, according to the question or ATQ :-

$\leadsto \sf 5 =\: 2 + a(20)$

$\leadsto \sf 5 - 2 =\: 20a$

$\leadsto \sf 3 =\: 20a$

$\leadsto \sf \dfrac{3}{20} =\: a$

$\leadsto \sf\boxed{\bold{\red{a =\: \dfrac{3}{20}\: m/s^2}}}$

✭ In case of mass :-

As we know that :

★ $\red{ \boxed{\sf{F =\: ma}}}$ ★

So, according to the question or ATQ :-

$\leadsto \sf 12 =\: m \times \dfrac{3}{20}$

$\leadsto \sf \dfrac{12}{\dfrac{3}{20}} =\: m$

$\leadsto \sf \dfrac{12}{1} \times \dfrac{20}{3} =\: m$

$\leadsto \sf \dfrac{240}{3} =\: m$

$\leadsto$ ${\small{\bold{\purple{\underline{m =\: 80\: kg}}}}}$

Henceforth, the mass of the body is 80 kg.

Correct options is C) 80 kg .